Intensities of emitted energies of hydrocarbons within earth formations are extremely low. Of course, the borehole logging equipment art has proposed use of semiconductor detectors for determining radiation levels of materials in and around a borehole associated with hydrocarbons. In U.S. Pat. No. 3,496,360, e.g., a semiconductor device for detecting nuclear radiation such as gamma rays is described in detail; but the purity of the desired spectrum can be subject to degradation from elements other than that being monitored. Consequently, the energy-resolving capabilities of the usual semiconductor devices have been found, in many cases, to be so low that desired characteristics associated with hydrocarbons cannot be resolved in the presence of usual background conditions. Detection of infrared radiation directly from hydrocarbons is more complex than detection of nuclear radiation. Reasons: water and other earth formation materials represent a serious background condition; hence infrared-radiation-resolving-capabilities of semiconductor devices are, in instances of which I am aware, extremely imprecise, especially where the infrared radiation being monitored is occurring because of differences in energy levels due to passive changes in thermal equilibrium within the formation.
Researchers hence heretofore have concentrated on obtaining a "generalized" knowledge of heat flow in a formation, preferably using an IR device located in a newly drilled borehole. In that way, passive emission measurements of IR energy can be obtained before heat equilibrium within the formation becomes established; see, e.g., U.S. Pat. No. 3,363,457 for "Methods of Measurement of Radiant Energy from Subsurface Formations," Ruehle et al.